Yes, the HEI module will suddenly quit if it doesn't get enough voltage. I think it happens somewhere around 9 volts, maybe 9.5 or 10.
Make sure you bypassed the ignition resistor to the HEI, it needs the full 12 volts, a common mistake when converting.

The "circuit board on the vacuum advance plate" I think you are refering to is the Module. I doubt it needs replacing, save your $35.

Yes, your alternator should have been able to put out enough charge to keep it running -- but -
If the battery had a major short in it, the alternator would not be able to keep up.
Especially if you still have the original Motorola alternator, it's weak to begin with.
Or, -- if you have converted to a GM alternator but have used the "quickie" wiring technique of the "single wire" or "jumper," it will be just as weak, the regulator won't see the discharged battery and will let you down.

Check to make sure it's charging correctly.

.

 

Thanks for the info. I'd like to think that the battery was the problem. I presume I should see something like 13.5 volts at the battery with the alternator kicked in. That should be a reasonable test that the alternator is working properly.

I got this Jeepster about two months ago so am still finding out the quirks it is possessed with.

PaulB
'67 Jeepster Convertible
'71 Jeepster SW

 

That will work. Turn on some stuff to see if the alt. will keep up. As long as you don't draw more than the alt. is rated for it should maintain 13.5 + or - .3 volts. If you don't have the GM alt. I highly recommend it. When I did mine it cost $13.00 and took 45 minutes. I found an alt. in a junk yard that looked new and was ready to go.
Good Luck, Chris

 

13.5 running is a little low, but it may be the accuracy of your meter.
Hook up the voltmeter, engine off. Start it, after a minute or so revved up a little, it should be at least a volt higher than it was.

Wired properly, battery fully charged, RPM 1200+, should go to about 14.6 - 14.8. Less than that won't fully charge the battery.

A fully charged battery with a "surface charge" will read from 13.2 - 13.6, engine and everything off.

 

That's the sort of info I need. Will check the voltages I see and get back with you.

Headed to the Shenandoah this week end for a cabin trip, its a walk in so the Jeepster stays home. I'll look at the voltages next week.

Thanks,


PaulB
'67 Jeepster Convertible
'71 Jeepster SW